The Difference Between An SSD And An HDD

By Mitz Pantic | Small Business

Technically, a Solid State Drive (SSD) is a particular type of Hard Disk Drive (HDD), but in common use, SSD and HDD mean two different types of devices. Here’s how SSDs and HDDs differ and why you should care.

Ye Olde Magnetic HDD

Invented in the 1950s, the original magnetic hard disk drives were the size of large refrigerators and held only a few megabytes of data. (The rough equivalent of a single 8 megapixel image from one of today’s digital cameras.)

Governments, universities, and businesses were eager to pay hundreds of thousands of dollars for those early magnetic HDDs because they were much faster at data storage and retrieval than the paper and magnetic tapes commonly used in those days. They could also hold hundreds or thousands of times as much data as computer memory (RAM) costing the same price.

Although magnetic HDDs have gotten smaller in size, bigger in storage capability, and much less expensive per megabyte, they’re still highly desired for the same reason. They’re faster than storing your data on CD-ROMs or floppy disks, and they still hold hundreds or thousands of times as much data as your computer memory for an equivalent price.

Meet The New Kid: SSDs

But just as magnetic HDDs supplanted paper and magnetic tape because HDDs were faster, SSDs are supplanting magnetic HDDs because SSDs are faster.

SSDs are solid state drives—that means they have no mechanical moving parts. The absence of moving parts in an SSD lets many parts of it operate at the speed of electricity, which is about 160,000 kilometers per second over standard copper wiring. No moving part on a magnetic hard drive can compete with that.

That’s not to say than SSDs are thousands of times faster than HDDs. There are a number of bottlenecks which limit the speed of SSDs, but high-end SSDs can run up to ten times faster than traditional HDDs. One thing people will have to get used to is the fact that SSD’s do not need de-fragmentation like the older hard drives do.

Mechanical Differences Between SSDs and HDDs

I mentioned that SSDs were a type of HDD and you may have noticed me saying “magnetic” before “HDD” everywhere in this article. That’s because Hard Disk Drive stands for hard(wired) disk drive—in other words, any disk drive which is not usually removed from the computer.

Most people today use HDD to refer to magnetic disk drives—any drive which uses a rotating magnetic platter to store its data. They also use Solid State Drive (SSD) to refer to any drive which uses solid state drive technology and connects to a standard hard drive port (such as SATA).

You can almost always tell an SSD and HDD apart by looking at an example of each.The Difference Between An SSD And An HDD

First, the SSD will probably be clearly labeled as such.

Second, a magnetic drive will almost always weigh more than an equivalent SSD.

Third, you can often see an outline of the circular area of the drive which holds the disk platters on an HDD.

Cost And Capacity Differences

Right now, SSDs cost more than magnetic HDDs with equivalent storage space (capacity). Also, the largest single magnetic hard drives typically have more storage space than the largest SSD drives. (But this is mostly a matter of cost: building a three terabyte SSD wouldn’t be difficult, but it would cost so much money that almost nobody would buy it).

As SSDs have become increasing popular over the last few years, their cost has dropped, so it’s possible that they will become the dominant storage technology sometime in the next decade and magnetic HDDs will disappear from common use like paper and magnetic tape did during the 1980s.